The Obama administration says sanctions against those backing separatists in eastern Ukraine are having an impact on the Russian economy, but the coming change of legislative power in Washington may affect U.S. policy toward the crisis.

Ukrainian forces fighting Russian-backed separatists are looking for more help from Europe and the United States at a time when Russian President Vladimir Putin may see President Barack Obama as weakened by electoral losses, the Atlantic Council’s Robert Manning said.

“We know, for example in the Ukraine, Putin looks like he is trying to strengthen his position in eastern Ukraine and break away Donetsk from the rest of the country, and he might be more encouraged to do that,” Manning said.

Putin faced little criticism on Ukraine at a meeting of Asia-Pacific leaders in Beijing, in part because of what former Putin adviser Andrei Illarianov, now a research fellow at the Cato Institute, called a “tactical pause” in the Russian offensive.

“This is partly the result of elections in the U.S. Congress and partly connected to Putin’s visit to Asia," he said. "It was probably a decision that escalating the conflict would create a bad atmosphere during Putin’s meetings with international leaders. But then after this visit, we will see an escalation.”

Republican Senator John McCain of Arizona, who is in line to chair the Senate Armed Services Committee, has been pushing Obama to take a harder line against Moscow. This could help the president, said Keith Darden, an associate professor in the School of International Service at American University in Washington.

"In some ways, it increases President Obama’s leverage in his negotiations with the Russians, to the extent that those exist, because basically there is always a threat that Congress is going to act on its own,” Darden said.

Eric Rubin, deputy assistant secretary of state for European and Eurasian affairs, said there is broad, bipartisan support for how to move forward on Ukraine.

“The key question is does Ukraine need help rebuilding its military and its national security infrastructure," Rubin said. "The answer is yes. And are we committed to helping them? Yes, we are, very publicly. There has been a significant amount of assistance. There will be more. The question is what, and that is the debate that is going on now.”

In that debate, the installation of new leaders in Ukraine’s breakaway regions could help fuel a Republican drive for stronger U.S. action, including sending weapons.

“If Congress gets involved," Darden said, "not only is it probably going to be more severe, including military aid and maybe some economic aid, it might be more significant sanctions on Russia, and they are much harder to undo.”

Prospects for tougher sanctions will be part of European Union talks in Brussels on Monday, said EU foreign policy chief Federica Mogherini.

“There will be a discussion there," Mogherini said, "but I would say not just on whether to increase the sanctions but most of all how to support Ukraine in these difficult times — difficult because of security on its territory.”

That security is threatened by troop movements along the Russian border, which German Foreign Minister Frank-Walter Steinmeier warns could lead to violent confrontations.